Welding rod



Patented May 15, 1928.

UNITED STATES 1,669,660 PATENT OFFICE.

J BIRCHARD GREEN, OF CHICAGO, ILLINOIS, ASSIGNOB T0 CHICAGO STEEL AND WIRE COMPANY OF CHICAGO, ILLINOIS, A CORPORATION 01' ILLINOIS.

WELDING ROD.

1T0 Drawing.

My invention has to do with filler rods which are used as electrodes in metallic arc welding, and is particularly concerned with the manner in which the surfaces of such rods are treated in order-to stabilize the are. In metallic arc welding, the working characteristics of any one type of electrode are subject to fairly wide variation, depending on the residual quantity of lime, a lubricant used in wire drawing, that happens 'to be left on the finished wire or electrode. The lubrication of wire during drawing to prevent its breaking into small pieces instead of passing through the dies in long continuous lengths, is a delicate thing. If the drawing of the wire must be made secondary to the leaving of a substantial quantity of the lime lubricanton the finished wire, the drawing cannot be accomplished with maximum economy,and, conversely, if the quantity of residual lime is disregarded, the finished electrode will vary in its working characteristics, this lack of uniformity making it difficult to use and at times preventing the welder from performing commercially acceptable work. Furthermore, if the finished electrode has been passed several times through the drawing dies, it is practically impossible to leave a substantial quantity of.

lime on the finished wire. It is often desirable, andin the lighter sizes absolutely necessary, to pass the wire many times through the dies.

It is a well known fact that metals, known as first class conductors, increase in electrical resistance as their temperature is elevated, while second class conductors, to which class lime belongs, decrease. Itis easy to understand that at the extremely high temperatures of the metallic are this effect hecomes very pronounced, and this accounts for the fact that the presence of some second class conductor is essential in connection with a metallic arc electrode if a commer cially stable arc is to be produced.

It has been the practice to apply a substantial quantity of second classconducting material to the surfaces of electrodes, whereby to produce an electrode which is completely sheathed in a so-called flux coating.-

When such asubstantia-l quantity is applied, however, the electrodes dry slowly and duringthe drying process must be kept out of contact with each other or at least a poor appearing product results and often one Application flled il arch 19, 1926. Serial m. 98,064.

which on account of wide variation in the quantity of flux at difierent points alon the electrode gives a wide variation in wor ing characteristics.

Full flux coatings may not only stabilize the are but in addition perform other functions as throwing the preponderance of heat to one pole or the other in direct current welding, as adding to or subtracting from the composition of the electrode passed metal, as forming an insulating coating,- advantages in welding at the bottom of deep narrow grooves, and the like.

One object of my invention is to provide a surface which produces practically the maximum of arc stability but which does not provide for any other appreciable influence on the are or the deposit as is possible with a full flux coating.

Another object is to provide a method of manufacture which will permit standardization of the electrode working characteristics so far as the stabilizing effect of surface' materials is concerned without substantially so treated in mass during both dipping and drying that this can be accomplished and still apply a somewhat thicker film than the maximum possible as a residual coating of lime left after wire drawing. I find that the are from electrodes treated in this manner is almost as stable as with a full flux coating; in fact, they can readily be used. for metallic arc welding with an alternating sixty cycle current source, which is not considered practical with the. ordinary bare electrode.

Electrodes made by my method can be ,produced as cheaply as bare electrodes because the cost of applying the second class conductor is offset, or may be more than ofiset, by the economies possible in the wire drawing, and more especially in the avoidance of rejections of electrodes too free from residual lime to give a commercially stable arc. Another advantage of my method is that it permits latitude in the selection of sec- 0nd class conductors while any that are left residual from wire drawing must primarily be proper wire mill lubricants. The most suitable second class conductors from the standpoint of stabilizing the are seem to fall in the vclass of the more stable salts, oxides and hydroxides of the alkaline earths and metals. The lime left on the wire after drawing air slakes in a comparatively short time and becomes essentially calcium carbonate. Partly bccause of this which means that the welding industry has had long experience with its use in the small quantities present on bare electrodes, and partly on account of its cheapness and ease in handling, I prefer to use'calciimi carbonate in my method of surfacing electrodes.

Both lime and calcium carbonate are quite opaque, or have, what painters call, good covering power. On this accountit is difi'icult to tell by inspection small differences in the thickness of the surface covering,

especially if this be thin, and yet such small difl'erencesresult in a substantial difference in the welding characteristics of electrodes. This permits confusion in a wire mill where electrodes are made by my method and other bare electrodes or other similarly drawn wires are made, and this is especially true if the quantity of residual lime is large and the finished wire has been wet with water. Confusion can also occur in the hands of the user of electrodes. To. overcome this I pre cipitate a small amount'of some pigment,

neutral so far as welding is concerned in the quantity used, on the calcium carbonate used this has never been used to distinguish any electrode coating.

In order to make the electrode surfacing contemplated by my method adherent, I use imum thickness to the surfacing possible by my method of treating the electrodes in mass. ater, 500 parts by weight; calcium carbonate, 325 parts by weight; green pigment, 25 parts by weight; adhesive, tosuit.

Definite proportion of the adhesive cannot be. specified because of the variable nature of both soap andsodium silicate. So little, however, should be used as to leave the finished electrode what might be termed slightly dusty, i. e. the pigmented calcium carbonate should not be glazed on the surface because adhesive in such quantity might influence welding.

I claim:

1. A process of coating welding rods which comprises dipping the rods in a bath comprising about 500 parts of water, about 325 parts of calcium carbonate, about 25 parts of a green pigment and a suitable amount of adhesive to give the desired consistency.

2; A process of coating welding rods which comprises dipping the rods in a bath containing a binder and about 325 parts of calcium carbonate to every 500 parts of water.

3. Welding rods having a weld-assisting coating resulting from being dipped in a. bath containing a binder and about 325 parts of calcium carbonate to every 500 parts of water.

In testimony whereof I have hereunto 

